Screen Print Reflection Transfer and Process for the Manufacture Thereof

ABSTRACT

The invention relates to a method for manufacturing a screen print reflection transfer product and to reflection transfer systems produced by this method. According to said method, the reflecting color is provided with a multitude of reflecting particles, said reflecting particles protruding from the surface of the top color coat.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation application under 35 U.S.C. 120 of U.S.Ser. No. 13/854,998 filed on Apr. 2, 2013, which is a continuationapplication of U.S. Ser. No. 12/899,605 filed on Oct. 7, 2010, which isa continuation application of U.S. Ser. No. 11/548,979, filed on Oct.12, 2006 (abandoned), which is a continuation of U.S. Ser. No.09/807,774, filed on Apr. 17, 2001 (U.S. Pat. No. 7,946,226), which is anational stage application of PCT international applicationPCT/EP99/08036 filed on Oct. 22, 1999, which claims priority from Germanpatent document 198 48 863.7 filed on Oct. 23, 1998 and German patentdocument 199 15 713.8 filed on Apr. 8, 1999. The disclosures of allthese patent documents are incorporated herein by reference in theirentireties.

FIELD OF INVENTION

The invention relates to reflection transfer systems and to a processfor the manufacture of a reflection transfer in the screen printingprocess. In accordance with the present invention, the term“reflection-transfer” refers to a transfer of which the reflectiveproperties are based on the use of an ink or carrier material, in whicha plurality of small reflecting particles are present.

BACKGROUND OF INVENTION

Said reflection inks have long been known. The reflection property ofthese inks is based on the fact that a plurality of small reflectingparticles are contained in the ink mass. Such particles can be ofspherical shape and consist of metal, glass, metal-coated glass, ormetal-coated plastic. A suitable ink is marketed, for example, by thecompany of Sericol under the commercial name “Reflec 100” and “Reflec200”.

Inks are also known in which the reflection particles are present in theform of chips.

In the meaning of the present invention, the term reflection inks isalso understood to mean colorless or transparent carriers and lacquers,as far as they contain reflection particles.

According to the prior art, such inks can only be used in the screenprint direct process without the reflection properties beingsubstantially impaired.

According to the screen print direct process, the reflection ink isapplied directly onto a substrate. Textile and plastic stripes may beused as substrates. The printing of processed textiles, such as shirts,jackets, and T-shirts, is likewise possible.

The known screen print direct process comprises the following processsteps:

1. Introducing and positioning the substrate to be printed into theprinting device;

2. optionally printing/applying a primer coating; and

3. Printing/applying the reflection ink.

Depending on the properties of the primer coating being used and of-thereflection ink, further drying steps between the individual processsteps can be provided.

By means of the screen print direct process, high-quality prints can bemanufactured on said substrates, whereby the reflection ink has-verygood reflection capability.

The screen print direct process however, has a plurality of drawbacks.The printing of made-up textiles such as shirts or jackets is extremelydifficult, since the seams being present or other applications to thetextile interfere with or impede the printing process. The exactpositioning of the textile to be printed in the printing device is alsonecessary which leads to an increased amount of work. Additionally, thepre-manufactured textiles must be sent to the printing office, whichcauses increased transport expenditure. The printing of small series ineach case involves the elaborate resetting of the printing device, whichis also disadvantageous.

In particular, due to the frequent customer's need for the printing ofsmall series which are then sold and may be required to be re-run,depending on the market demand, the need for the printing device to beequipped in each case with the corresponding printing devices leads toan increased amount of work and increased costs.

In order to meet customer s requirements for small series which can bere-run, to achieve higher machine utilization by reduced setting-uptimes, and to create the possibility, to make the application onto thesubstrate independent from the location of the printing device, transfersystems are known to be used.

The known screen print transfer systems are manufactured and used asfollows:

Providing a transfer carrier, e.g. of siliconised or waxed paper;

Applying/imprinting the ink; and

Applying/imprinting an adhesive.

If it is intended that motifs are to be manufactured with said transfersystems, the motifs are to be printed onto the transfer carrier in amirror-reversed fashion.

Such transfer systems can be manufactured in a simple manner, atreasonable cost and in large numbers.

The transfers manufactured can be sent to the customer and applied atthat location, according to demand, by means of a simple transfer press,onto the desired substrates. In this respect, it is possible for the endpurchaser to select a motif from a plurality of pre-prepared transfers,and to have the transfer applied onto a substrate being alsoindividually selected by him. Using such transfer systems, it ispossible for substrates to be prepared at almost any desired saleslocations which are provided with motifs in accordance with thecustomer's needs.

Application is effected by the substrate being brought into the transferpress and positioned, the transfer having the adhesive coating beingapplied onto the substrate and positioned, the transfer being applied onthe substrate by means of the transfer press with the aid of pressureand, if necessary, increased temperature, the substrate provided withthe motif being removed from the transfer press and the transfer carrierbeing removed from the substrate.

It has been shown, however, that, using reflection inks in the knownscreen print transfer systems, the reflection inks provide hardly anyreflection properties any longer after application onto the substratewhich is undesirable.

DE-AS 14 46 828 discloses a process for the manufacture of a reflectivetransfer film, and the transfer films manufactured thereby, in which, ona carrier coated with a plastic softened in the heat, sphericalreflection particles are incorporated under the effect of heat into thesurface of the plastic coating. Next, a sequence of layers of a rubberbinding agent, an optional heat blocking layer, an adhesive, and finallya second carrier is applied. Application is effected by the second layerbeing removed and the exposed adhesive side being bonded to the textilesubstrate under the application of heat. Finally, the plastic-coatedcarrier is removed.

U.S. Pat. No. 3,420,597 discloses a process for the manufacture of ahighly reflective coating on a rigid substrate, such as a road sign. Inthis case, an ink containing fully metal-coated micro-spheroids isapplied onto the substrate, whereby, after the ink mass has dried, themicro-spheroids are raised above the surface of the ink layer. In afurther processing step, the metal coating of the spheroids whichprojects beyond the ink layer, is removed by etching, as a result ofwhich an especially advantageous reflection capability is achieved.

U.S. Pat. No. 5,631,064 describes a process for the manufacture of areflection transfer in which a backing layer is first applied, ontowhich a plastic layer capable of being softened under heating isapplied, wherein reflecting spheroids are present in about 30-40% oftheir extent. Optionally, a mirror layer can be applied to the surfaceof the spheroids. In a two-step process, an artificial resin-bindingagent is first applied to the surface of the spheroids, and then atransfer adhesive is imprinted. For a figurative representation, theprint is to be applied in a mirror-reversed fashion.

The transfer is brought to application onto a substrate, such as atextile, with the transfer adhesive agent side and adhesively bonded inplace. Finally, the backing layer with the heat-softenable plastic layeris removed, whereby the spheroids remain in the hardened binding agentlayer.

AT-P-200 691 describes a fluid reflective coating agent, with which areflection is effected by a plurality of small glass or metal particles.

The object of the present invention is to overcome the disadvantages ofthe prior art and to provide a screen print reflection transfer systemand a process for the manufacture thereof, in which the reflection inkprovides substantial reflection properties after transferring onto thesubstrate.

A further object of the present invention relates to the provision of ascreen print reflection transfer system and a process for themanufacture thereof, whereby at least a part of the reflection particlesof the reflection ink used according to the invention are raised abovethe dried ink layer.

The objects of the invention are achieved by the limitations of theindependent claims. Preferred embodiments are presented in the dependentclaims.

SUMMARY OF INVENTION

In this case, the invention is based on the perception that thereflections with the-reflection inks used according to the invention areachieved essentially by reflection particles which are raised above thesurface of the hardened ink layer. In the meaning of the presentinvention, it is understood in this context that at least a part of thereflection particles being used project with a part of their surface outof the surface of the carrier layer.

The process for the manufacture of a screen print reflection transfersystem according to the invention proceeds as follows:

First, a primer carrier, referred to hereinafter as the base medium, isplaced for the transfer which is to be applied. The base medium canusually consist of a paper or plastic film with a surface which repelsadhesives. The adhesive-repellant properties are achieved bysiliconising or waxing the base medium. As base medium, all conventionaland known adhesive-repellant films and strips can be used whereby theonly restriction which applies is that the surface of the base medium issufficiently adhesive-repellant in order to guarantee thenon-destructive release of the adhesive layer being applied. A suitablebase medium is marketed, for example, by the company of B. LaufenbergGmbH under the commercial name NP 950.

In the screen print process, a transfer adhesive is imprinted on theadhesive-repelling surface of the base medium. The imprinting is carriedout in this case with the correct side to accord with the motif desired.This is possible for different, freely-selectable motifs, as a surfaceor even free-standing. The term “free-standing motifs” is understood tomean motifs which consist of at least two parts not connected to oneeach other.

As adhesive agents, conventional heat-sensitive and/orpressure-sensitive adhesives for screen print transfer systems may beused. A suitable adhesive agent is, for example, the adhesive availableunder the commercial name Metratan FT 421 from the company Sericol Co.

The adhesive agents can be, in particular in the hardened state,transparent, translucent, colored translucent, or colored-covering.

In a preferred embodiment, the adhesive agent is colored white. Due tothe white basis thus prepared, on which the reflection ink will beapplied later, a transfer can be manufactured with which, after theapplication on the substrate, the constituents of the reflection inkwhich provide the color can be utilized in a particular advantageousmanner.

Due to the use of a white basis, the coloring effect is reinforced, thecolors become more intense, and the color sequences are more uniform.The reflections also appear more strongly.

In particular, a possibly interfering influence from the substrate's owncolor on the colored appearance of the transfer will be avoided as aresult.

In an optional process step, the adhesive agent layer can be dried onthe base medium. This can be effected by means of a drying stretch oranother known possibility.

In the following process step, the reflection ink is imprinted on theadhesive agent layer in the screen print process. If it is intended thata motif should be displayed, it is imprinted with the correct side in aplan view. The print can be effected in the conventional manner in oneor more colors.

Following, a drying step is carried out, in which the printed reflectionink and, if applicable, the adhesive agent layer, is dried. This can beeffected by a drying stretch or other known possibilities.

The finished transfer, being formed from the adhesive agent layer andthe reflection ink and being present on the base medium, can be coatedor covered over, preferably full-surface, with a self-adhering flexibletransfer medium. The inherently known transfer medium may consist of afilm or a paper, coated with a conventional transfer adhesive. After thetransfer medium has been mounted, the transfer can be brought to theapplication step. The application step in this context is not boundeither temporally or spatially to the manufacture of the transfer.

For the applying step, the base medium is removed from the transfer andthe layer of the adhesive agent is exposed. The transfer is placed onthe substrate with the adhesive layer and imprinted on it with atransfer press, using heat and/or pressure. In this case, the adhesivecombines with the individual substrate. In the home sector, transferringcan even be carried out by means of a laundry iron, for example.

Finally, the transfer medium is removed from the now coated substrate,after cooling if appropriate.

The reflection inks used in the process according to the invention areinks of which the reflection capabilities for impinging light are basedon the fact that reflecting particles are present in the ink mass. Thereflecting particles may consist of metal, glass, metal-coated glass, ormetal-coated plastic. The reflection particles can be spherical oralmost spherical, or take the form of chips or needles. The diameter ofthe spherical or almost spherical particles is in the range from 10 to110 μm, preferably from 25 to 40 μm. The longitudinal extension of thechips or needles is in the range from 10 to 110 μm, and preferably from40 to 80 μm.

The ink mass may further contain one or more pigments, as a result ofwhich the appearance and impression in daylight is improved. Thereflection also appears colored in darkness.

The process according to the invention makes use, in an advantageousmanner, of the realization that, due to the process step of drying thereflection ink applied, the reflection properties are clearly improved.By means of this step, a transfer is manufactured which has the handlingadvantages of a transfer and, at the same time, provides a reflectioncapability which has hitherto only been achieved by the direct screenprint process.

Without any intention to be restricted to this, it is assumed that, bythe process step of drying and hardening, the situation is reached thatthe reflection particles-raised above the ink layer are fixed in thisposition. This effect is supported by the fact that, during the dryingprocess, a volume loss of the ink layer and thereby, a reduction in thethickness of the layer, in particular by the loss of water and/orsolvents, occur. Due to the reduction in the layer thickness during thedrying and hardening process respectively, it may happen that furtherreflection particles protrude from the surface of the ink layer and aretherefore available for the purpose of reflection. The reflectionparticles may protrude by about 30% of their diameter or theirlongitudinal extension from the surface of the dried ink layer.

In a further embodiment of the present invention, an additionalintermediate layer of an ink is imprinted on the adhesive agent layer,said ink not being a reflection ink.

The reflection ink is then imprinted on this intermediate layer.

Imprinting of the intermediate layer on the adhesive agent layer and/orthe imprinting of the reflection ink on the intermediate layer can, asbefore, be carried out as wet-on-wet or with drying steps interspersed.

The intermediate layer can be formed by imprinting any desiredsingle-component or two-component printing inks for the screen-printingprocess. The ink used for the formation of the intermediate layer ispreferably a high-covering ink, whereby, depending on the motif or coloreffect which is desired, any desired color shade can be chosen. Suitableinks are marketed under the commercial name NB 021 from the companySericol Co. and under the commercial name Maraflor TK from the companyMarabu Co.

The ink for the formation of the intermediate layer can be imprinted inthe same thickness as the adhesive agent layer and/or the reflectionink, but the layer thickness is preferably from 5 to 50 μm, and morepreferably from 10 to 20 μm.

Due to the use of the intermediate layer referred to, a transferaccording to the invention is formed which, in comparison with thetransfer according to the invention without an intermediate layer,provides increased tensile strength and tear resistance. The printinginks used as the intermediate layer also usually provide a higher inkcoverage than colored transfer adhesive agents, as a result of which theadvantageous properties such as are obtained with the use of coloredtransfer adhesives, are achieved to an enhanced degree.

The combination of an adhesive layer made of a transparent ortranslucent adhesive with a high-covering intermediate layer of whiteink is particularly advantageous. When applying the transfer onto thesubstrate, in particular using hot transfer under pressure, the adhesiveagent can flow into the upper layer of the substrate and emerge in smallquantities laterally between the transfer and the substrate and form anedge around the transfer which has been applied. Using a coloredadhesive agent may lead to undesirable colored edges. Using thecombination referred to heretofore, there is no flowing of the hardenedintermediate ink layer, so that no colored edge is formed around thetransfer which has been applied. Emerging colorless adhesive does indeedcontinue to form an edge around the transfer which has been applied, butin this case, no undesirable colored edge is formed due to thetransparency of the adhesive agent.

In a further embodiment, the reflection ink and the transfer adhesivecan be applied to the base medium in a single process step. In thiscase, the optional intermediate layer for a separate ink application canbe omitted.

For the joint application of the adhesive agent and the reflection ink,a mixture of the two can be manufactured, whereby the mixture is thenapplied in a single process step.

The adhesive agent/reflection ink mixture according to the presentinvention is also to be understood to mean formulations which arealready pre-manufactured and which comprise a transparent, translucent,or colored adhesive agent, as well as the reflection particles. Thetransfer adhesive on a plastisol base containing the reflectionparticles is in particular well suitable. Such plastisol adhesivescontaining reflection particles are known and are marketed commercially.

In the embodiment in which the transfer adhesive agent/reflection inkmixture or the transfer adhesive agent containing reflection particlesis applied in a single step, the process adopted is the following:

First, the base medium with an adhesive-repellent surface is applied.The transfer adhesive/reflection mixture or the transfer adhesivecontaining reflection particles is imprinted on the adhesive-repellentsurface in the screen print process.

As far as motifs are to be represented, they are imprinted with thecorrect side. Using multi-colored motifs, the individual coloredtransfer adhesive/reflection ink mixtures or transfer adhesivescontaining reflection particles are imprinted on the respective areas ofthe base medium, Using multi-colored motifs, the print can be effectedwet-on-wet, or the individual areas can be dried between the individualprinting steps.

Finally, a drying step is carried out, in which the reflection particlesare raised in the manner described heretofore above the surface of theimprinted mixture or adhesive agent, as far as this has not alreadytaken place in the optional intermediate drying steps.

The finished transfer which is located on the base medium can, asdescribed heretofore, be drawn over with a self-adhesive flexibletransfer medium.

This embodiment provides the further advantage that, during themanufacture of the transfer, one process step, namely applying orprinting of a separate transfer adhesive layer, can be omitted.

On the other hand, using transfers of this kind having one printed layeronly, particular care must be taken when applying by the use of atransfer press, since the adhesive is softened during the-application inorder to be applied onto the surface of the substrate or in order to beable to penetrate into it. At the same time, the bed in which thereflection particles are embedded and above the surface of which theyare to be raised is likewise softened. During the application, cautionis also to be exercised to ensure that the pressure of the transferpress or the like on the raised reflection particles is not so high thatthey are pressed completely into their bed, as a result of which thereflection property would to a large extent be lost. A slight imprintingof the reflection particles on the softened bed can however be effectedwithin the scope of the invention, provided that the reflectionproperties are not substantially influenced in a disadvantageous manner.

The invention is explained on the basis of figures and embodimentshereinafter in more detail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a transfer, which was manufactured according to the processaccording to the invention, after the process step of the drying of thereflection ink.

FIG. 2 shows a transfer which was manufactured according to the processaccording to the invention with a transfer film applied.

FIG. 3 shows a transfer which was manufactured according to the processaccording to the invention which has been applied to a substrate and isexposed to light.

FIG. 4 shows a transfer according to the prior art in which thereflection ink has been applied onto the transfer carrier.

FIG. 5 shows a transfer according to the prior art according to FIG. 4whereby a transfer adhesive has further been applied.

FIG. 6 shows a transfer according to the prior art which has beenapplied to the substrate and is exposed to light.

FIG. 7 shows a transfer manufactured according to the process accordingto the invention after the process step of the drying of the reflectionink, whereby an intermediate layer is located between the adhesive agentlayer and reflection ink layer.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a transfer after the process step of drying the ink layerconsisting of the base medium 1 onto which the transfer adhesive 2 isimprinted in the screen print process. The ink layer 3 is imprinted onthe transfer adhesive 2 with the correct side in the screen printprocess. At least a part of the reflection particles 4 contained in theink layer 3 are raised by part of their circumference above the exposedsurface of the dried and hardened ink layer.

FIG. 2 shows a reflection transfer as in FIG. 1 manufactured accordingto the process according to the invention, whereby a transfer film 5provided with an adhesive agent has been additionally applied on the inklayer 3. In this case, the reflection particles 4 are no longer pressedby means of the transfer film 5 into the hardened ink-layer 3.

FIG. 3 shows a reflection transfer manufactured according to the processaccording to the invention and comprising the transfer adhesive 2, thedried and hardened ink layer 3 with the raised reflection particles 4,whereby the transfer is applied onto the substrate 6. The impinginglight rays 7 which are reflected by the reflection particles 4 can beseen additionally.

FIG. 4 shows a transfer according to the prior art in the manufacturingstep, whereby the reflection ink 3′ is applied onto the transfer carrier5′. In this case, the side of the ink layer 3′, later forming thesurface turned towards the light, is turned towards the transfer carrier5′. The reflection particles 4′ are raised up on the side of the inklayer 2′ and being directed towards the substrate later. Due to thecontact of the ink layer 3′ with the transfer carrier 5′, the reflectionparticles 4′ cannot protrude from the later external surface of the inklayer 3′.

FIG. 5 shows a transfer according to the prior art in the manufacturingstep, in which the transfer adhesive 2′ has been applied onto thereflection ink 3′. In this case, it can be recognized that thereflection particles 4′ raised above the surface of the ink layer 3′ areembedded into the transfer adhesive 2′.

FIG. 6 shows a transfer according to the prior art which is applied to asubstrate 6, whereby the transfer adhesive 2′ is located between thesubstrate 6 and the ink layer 3′. The side of the ink layer 3′ directedtowards the impinging light 7 does not provide any raised reflectionparticles 4′. Due to the reflection particles 4′ embedded in the inklayer 3′ and the transfer adhesive 2′, the impinging light beam 7 isonly inadequately reflected back and shows practically no reflectioneffect.

FIG. 7 shows a transfer according to the invention after the operationalstep of drying the ink layer, consisting of the base medium 1 on whichthe transfer adhesive 2 is imprinted in the screen print process. In thescreen print process, the intermediate layer 8 is imprinted on thetransfer adhesive 2 with the correct side. The ink layer 3 is imprintedon the intermediate ink layer 8. At least a part of the reflectionparticles 4 contained in the ink layer 3 protrude with a part of theircircumference from the exposed surface of the dried and hardened inklayer.

EXAMPLES Embodiment 1

In a fully-automatic screen printing machine equipped with a screenprinting frame with a fabric stretch of 21-77, a doctor blade ofmultilayered polyurethane and a float blade of metal, a silicone-coatedpaper of the type NP 950 from Laufenberg GmbH is placed as the basemedium. Next, a transfer adhesive of the type FT 421 from the companySericol Co. is imprinted in a layer thickness of 100 to 300 μm. Thetransfer adhesive is dried in a drying stretch with an infra-red dryerat a drying temperature of between 80-120° C. The reflection ink or amixture of reflection inks is imprinted on the transfer adhesive in awet layer thickness of 100 to 300 μm. Drying then takes place in adrying stretch with an infra-red dryer at a drying temperature ofbetween 80-120° C. A transfer medium is applied onto the finishedtransfer, made of a paper provided with adhesive.

Embodiment 2

In a screen printing machine as was used in Example 1, a silicone-coatedpaper of the type NP 950 from Laufenberg GmbH is placed as the basemedium. Following, a transparent transfer adhesive of the type MetratonFT 421 from the company Sericol Co. is imprinted in a layer thicknessfrom 100 to 200 μm and is dried in a drying stretch with an infra-reddryer at a temperature of between 80-120° C. An intermediate layer about20 μm thick of NB 021 from the company Sericol Co. is imprinted on thetransfer adhesive in a white color tone and is likewise dried. Areflection ink of the type Reflek 100 from the company Sericol Co. isimprinted on the dried intermediate layer in a thickness from 100 to 120μm. This is followed by air drying. A transfer medium made of a paperprovided with an adhesive is applied onto the finished transfer.

Embodiment 3

In a screen printing machine as used in Example 1, a silicone-coatedpaper of the type NP 950 is placed as the base medium. Then, reflectionparticles-containing a colored transfer adhesive are imprinted in alayer thickness from 100 to 250 μm and dried in a drying stretch at atemperature of between 50° C. and 120° C. A transfer medium of a paperprovided with an adhesive agent is applied onto the finished transfer.

1. A reflection transfer, comprising: a finished transfer having thefollowing layer sequence before application to a substrate: anadhesive-repellant base medium; a transfer adhesive on said base medium;an exposed hardened reflection ink on said transfer adhesive, saidhardened reflection ink comprising reflection particles that are raisedabove the surface of the hardened reflection ink, and wherein saidreflection ink forms a motif with a correct side in a plan view.
 2. Thereflection transfer as in claim 1, wherein the adhesive-repellent basemedium comprises a paper or plastic film coated with a silicone or wax.3. The reflection transfer as in claim 1, wherein the transfer adhesivecomprises a heat-sensitive or pressure sensitive adhesive.
 4. Thereflection transfer as in claim 1, wherein the transfer adhesive istransparent or translucent.
 5. A reflection transfer, consisting of: abottom layer comprising an adhesive-repellant base medium; a middlelayer comprising a transfer adhesive; and a top layer comprising areflection ink having reflection particles that are raised above thesurface of the hardened reflection ink, said reflection ink layerforming a motif that is imprinted with a correct side in a plan view. 6.The reflection transfer as in claim 5, wherein the adhesive-repellentbase medium comprises a paper or plastic film coated with a silicone orwax.
 7. The reflection transfer as in claim 5, wherein the transferadhesive comprises a heat-sensitive or pressure sensitive adhesive. 8.The reflection transfer as in claim 5, wherein the transfer adhesive istransparent or translucent.